Structural materials for nuclear reactors ...
Document type :
Autre communication scientifique (congrès sans actes - poster - séminaire...): Poster
Permalink :
Title :
Structural materials for nuclear reactors cooled with liquid Pb or Pb-Bi: their behavior in the presence of liquid metal and under mechanical stress
Author(s) :
Conference title :
HTCPM (High Temperature Corrosion and Protection of Materials) symposium
City :
Les Embiez
Country :
France
Start date of the conference :
2024-06
English abstract : [en]
The durability of the structural materials at high temperature, under irradiation, under mechanical stress and in the presence of the heat transfer fluid, is one of the challenges in the development of 4th generation nuclear ...
Show more >The durability of the structural materials at high temperature, under irradiation, under mechanical stress and in the presence of the heat transfer fluid, is one of the challenges in the development of 4th generation nuclear reactors, especially reactors cooled by liquid lead (LFR) or for the development of ADS (Accelerator Driven Systems) which use liquid lead-bismuth eutectic (LBE). For these two types of reactors, in addition of damage due to irradiation, one of the major damages to structural materials could be due to corrosion by liquid metal. Additionally, under stress (mechanical stress or stress due to temperature fluctuations), structural materials can be susceptible to liquid metal embrittlement (LME) or liquid metal accelerated damage (LMAD), i.e. partial or total loss of ductility in the presence of liquid metal and therefore an earlier fracture [1]. Thus, although tough and ductile metallic alloys are selected, they may become brittle when stressed in liquid metal exhibiting thereby the so-called LME.The objective of the presentation is to summarize the knowledge acquired at UMET over more than 20 years [2-10] on the mechanical behavior of coated or uncoated metallic alloys (martensitic and austenitic) in the presence of liquid Pb or LBE and then to present the main conclusions and the main issues for future researches. Thus, to investigate the behavior of the materials in presence of liquid metal, their mechanical properties were investigated in temperatures range from 200°C to 550°C by carrying out monotonic tests (Small Punch Tests and tensile tests) and Low Cycle Fatigue tests in air and in liquid LBE or/and liquid lead. Attention was paid to the influence of different parameters including the composition of the liquid metal (Pb, LBE, Bi), the oxygen content in the liquid metal and the strain rate. Indeed, the oxygen content of the liquid metal affects the interface between the steel and the liquid metal by formation of an oxide layer (high oxygen) or decreasing the possibility of protective oxide layer formation (low oxygen). Furthermore, variations in oxygen content or chemistry of the liquid metal (Pb, LBE, Bi) could lead to a modification of adsorption or absorption mechanisms. The mechanical properties in inert environment depend on the strain rate. The time immersion in the liquid metal is affected by the strain rate. So, the strain rate could be considered as an important parameter concerning the mechanical behavior of the metallic alloys in contact with lead and LBE. After mechanical tests, the fracture surfaces and the cracking were analyzed by SEM (Scanning Electron Microscopy), EDX-SEM (Energy-Dispersive X-Ray), EBSD (Electron BackScatter Diffraction) or ToF-SIMS (Time of-Flight Secondary Ion Mass Spectrometry) to characterize and understand the effect of the liquid metal on the damage at the scale of the microstructure. The martensitic T91 steel with Body-Centered Cubic (BCC) structure suffers from LME in lead as in LBE. A ductility trough and so an effect of the temperature due to the presence of liquid metal could be observed for temperatures between the fusion temperature of the liquid metal and 450 / 500 °C, with a most important sensitivity around 300°C 350°C. The existence, the depth, the bottom, the length of this ductile trough depend on the different parameters which influence the LME sensitivity especially the strain rate, the oxygen content in Pb or LBE, the surface roughness, the nature of oxide layer or the presence of a protective coating, the microstructure state and the hardness of the steel. But the most influential parameter is the strain rate. Low strain rate promotes sensitivity to LME. In addition, the presence of defects at the surface due to corrosion by the liquid metal (pits, micro-cracks …) promotes the LME sensitivity of the T91 steel not only under monotonic loading but also under cyclic loading. The austenitic steels (316L, 15-15Ti, alumina-forming austenite (AFA) steels) appear less sensitive to LME for temperature up to 450 °C. But, for an AFA steel, LME sensitivity was observed at temperatures above 500 °C with intergranular brittle fracture in presence of liquid metal. New FeCrNiMn alloys with a Face-Centered Cubic (FCC) structure are sensitive to LME by Pb and LBE. Note that in the same conditions, the materials are less sensitive to LME in liquid lead in comparison with LBE without simple link with the Bi content. In the literature, three different mechanisms have been proposed to explain LME [1,11,12]: 1. LME explained by atomic interactions between the liquid metal and the metallic alloy, especially by adsorption and so liquid metal assisted interfacial cracking or liquid metal-assisted dislocation emission modification, 2. LME explained by grain boundary wetting and decohesion, at grain boundaries, 3. LME due to liquid metal corrosion. The LME of the T91 steel is explained by adsorption of Pb and/or Bi atoms at the surface of the metallic materials and so a reduction of the metallic material surface energy and adsorption-induced reduction of the bond strength and/or an adsorption-induced dislocation emission modification. This mechanism also explains the low sensitivity to LME of the 15-15Ti and 316L steels, but not the intergranular cracking observed for some FCC alloys in presence of liquid metal which could be explained by grain boundary wetting models. References 1. T. Auger, J-B. Vogt, I. Proriol Serre, Metal liquid Embrittlment, Mechanics - Microstructure - Corrosion Coupling, 1st Edition, Concepts, Experiments, Modeling and Cases, Editors: Christine Blanc Isabelle Aubert, STE Press –Elsevier, 2019. 2. A. Verleene, J.-B. Vogt, I. Serre, A. Legris, International Journal of Fatigue. 28, 843-851 (2006). 3. J-B., Vogt, A. Verleene, I. Serre, F. Balbaud-Célérier, L. Martinelli, A. Terlain, Engineering Failure Analysis. 14, 1185-1193 (2007). 4. I. Serre, J.-B. Vogt, Journal of Nuclear Materials. 376, 330-335 (2008). 5. I. Proriol Serre, I. Diop, N. David, M. Vilasi, J-B. Vogt, Surface and Coatings Technology. 205, 4521-4527 (2011). 6. C. Ye, J-B. Vogt, I. Proriol Serre, Materials Science & Engineering A. 608, 242-248 (2014). 7. I. Proriol Serre, J-B. Vogt, N. Nuns, Applied Surface Science. 471, 36-42 (2019). 8. J-B. Vogt, J. Bouquerel, C. Carlé, I. Proriol Serre, International Journal of Fatigue. 130, 105265 (2020). 9. I. Proriol Serre, J-B. Vogt, Journal of Nuclear Materials., 152021 (2020). 10.I. Proriol Serre, J-B. Vogt, Engineering Failure Analysis. 139 (2022). 11. D. Kolman, David, Corrosion. 75,(1) 42‑57 (2019). 12.J.E. Norkett, M. D. Dickey, V. M. Miller, Metallurgical and Materials Transactions A 52, (6), 2158‑72 (2021).Show less >
Show more >The durability of the structural materials at high temperature, under irradiation, under mechanical stress and in the presence of the heat transfer fluid, is one of the challenges in the development of 4th generation nuclear reactors, especially reactors cooled by liquid lead (LFR) or for the development of ADS (Accelerator Driven Systems) which use liquid lead-bismuth eutectic (LBE). For these two types of reactors, in addition of damage due to irradiation, one of the major damages to structural materials could be due to corrosion by liquid metal. Additionally, under stress (mechanical stress or stress due to temperature fluctuations), structural materials can be susceptible to liquid metal embrittlement (LME) or liquid metal accelerated damage (LMAD), i.e. partial or total loss of ductility in the presence of liquid metal and therefore an earlier fracture [1]. Thus, although tough and ductile metallic alloys are selected, they may become brittle when stressed in liquid metal exhibiting thereby the so-called LME.The objective of the presentation is to summarize the knowledge acquired at UMET over more than 20 years [2-10] on the mechanical behavior of coated or uncoated metallic alloys (martensitic and austenitic) in the presence of liquid Pb or LBE and then to present the main conclusions and the main issues for future researches. Thus, to investigate the behavior of the materials in presence of liquid metal, their mechanical properties were investigated in temperatures range from 200°C to 550°C by carrying out monotonic tests (Small Punch Tests and tensile tests) and Low Cycle Fatigue tests in air and in liquid LBE or/and liquid lead. Attention was paid to the influence of different parameters including the composition of the liquid metal (Pb, LBE, Bi), the oxygen content in the liquid metal and the strain rate. Indeed, the oxygen content of the liquid metal affects the interface between the steel and the liquid metal by formation of an oxide layer (high oxygen) or decreasing the possibility of protective oxide layer formation (low oxygen). Furthermore, variations in oxygen content or chemistry of the liquid metal (Pb, LBE, Bi) could lead to a modification of adsorption or absorption mechanisms. The mechanical properties in inert environment depend on the strain rate. The time immersion in the liquid metal is affected by the strain rate. So, the strain rate could be considered as an important parameter concerning the mechanical behavior of the metallic alloys in contact with lead and LBE. After mechanical tests, the fracture surfaces and the cracking were analyzed by SEM (Scanning Electron Microscopy), EDX-SEM (Energy-Dispersive X-Ray), EBSD (Electron BackScatter Diffraction) or ToF-SIMS (Time of-Flight Secondary Ion Mass Spectrometry) to characterize and understand the effect of the liquid metal on the damage at the scale of the microstructure. The martensitic T91 steel with Body-Centered Cubic (BCC) structure suffers from LME in lead as in LBE. A ductility trough and so an effect of the temperature due to the presence of liquid metal could be observed for temperatures between the fusion temperature of the liquid metal and 450 / 500 °C, with a most important sensitivity around 300°C 350°C. The existence, the depth, the bottom, the length of this ductile trough depend on the different parameters which influence the LME sensitivity especially the strain rate, the oxygen content in Pb or LBE, the surface roughness, the nature of oxide layer or the presence of a protective coating, the microstructure state and the hardness of the steel. But the most influential parameter is the strain rate. Low strain rate promotes sensitivity to LME. In addition, the presence of defects at the surface due to corrosion by the liquid metal (pits, micro-cracks …) promotes the LME sensitivity of the T91 steel not only under monotonic loading but also under cyclic loading. The austenitic steels (316L, 15-15Ti, alumina-forming austenite (AFA) steels) appear less sensitive to LME for temperature up to 450 °C. But, for an AFA steel, LME sensitivity was observed at temperatures above 500 °C with intergranular brittle fracture in presence of liquid metal. New FeCrNiMn alloys with a Face-Centered Cubic (FCC) structure are sensitive to LME by Pb and LBE. Note that in the same conditions, the materials are less sensitive to LME in liquid lead in comparison with LBE without simple link with the Bi content. In the literature, three different mechanisms have been proposed to explain LME [1,11,12]: 1. LME explained by atomic interactions between the liquid metal and the metallic alloy, especially by adsorption and so liquid metal assisted interfacial cracking or liquid metal-assisted dislocation emission modification, 2. LME explained by grain boundary wetting and decohesion, at grain boundaries, 3. LME due to liquid metal corrosion. The LME of the T91 steel is explained by adsorption of Pb and/or Bi atoms at the surface of the metallic materials and so a reduction of the metallic material surface energy and adsorption-induced reduction of the bond strength and/or an adsorption-induced dislocation emission modification. This mechanism also explains the low sensitivity to LME of the 15-15Ti and 316L steels, but not the intergranular cracking observed for some FCC alloys in presence of liquid metal which could be explained by grain boundary wetting models. References 1. T. Auger, J-B. Vogt, I. Proriol Serre, Metal liquid Embrittlment, Mechanics - Microstructure - Corrosion Coupling, 1st Edition, Concepts, Experiments, Modeling and Cases, Editors: Christine Blanc Isabelle Aubert, STE Press –Elsevier, 2019. 2. A. Verleene, J.-B. Vogt, I. Serre, A. Legris, International Journal of Fatigue. 28, 843-851 (2006). 3. J-B., Vogt, A. Verleene, I. Serre, F. Balbaud-Célérier, L. Martinelli, A. Terlain, Engineering Failure Analysis. 14, 1185-1193 (2007). 4. I. Serre, J.-B. Vogt, Journal of Nuclear Materials. 376, 330-335 (2008). 5. I. Proriol Serre, I. Diop, N. David, M. Vilasi, J-B. Vogt, Surface and Coatings Technology. 205, 4521-4527 (2011). 6. C. Ye, J-B. Vogt, I. Proriol Serre, Materials Science & Engineering A. 608, 242-248 (2014). 7. I. Proriol Serre, J-B. Vogt, N. Nuns, Applied Surface Science. 471, 36-42 (2019). 8. J-B. Vogt, J. Bouquerel, C. Carlé, I. Proriol Serre, International Journal of Fatigue. 130, 105265 (2020). 9. I. Proriol Serre, J-B. Vogt, Journal of Nuclear Materials., 152021 (2020). 10.I. Proriol Serre, J-B. Vogt, Engineering Failure Analysis. 139 (2022). 11. D. Kolman, David, Corrosion. 75,(1) 42‑57 (2019). 12.J.E. Norkett, M. D. Dickey, V. M. Miller, Metallurgical and Materials Transactions A 52, (6), 2158‑72 (2021).Show less >
Language :
Anglais
Audience :
Internationale
Popular science :
Non
Administrative institution(s) :
Université de Lille
CNRS
INRAE
ENSCL
CNRS
INRAE
ENSCL
Collections :
Research team(s) :
Métallurgie Physique et Génie des Matériaux
Submission date :
2024-08-18T13:16:38Z